In the prior art, electrically powered lamps, for example, arc lamps, are commonly used to illuminate a movie scene, a theatrical set, a musical or television production, or the like. The lamp is typically mounted within an enclosure adjacent to a reflecting mirror and arranged so as to cast light through a Fresnel lens mounted on the enclosure. The reflecting mirror and lamp are movably mounted so as to permit the light cast by the lamp to either "flood" a scene or merely to cast a "spot" of light or something between these two extremes.
The lamp used in such applications is usually rated at several hundred or thousand watts and, in the prior art, only a portion of the light generated by the lamp is projected through the lens. A significant portion (up to two-thirds or even more) of the light is lost within the enclosure, causing the enclosure to heat significantly. This results not only in lost or wasted power, but also the excessive heating of the enclosure and its components. The lamp itself may be an arc lamp, quartz lamp, metal halide lamp or any other type of lamp.